Simply defined, a virus is a self-replicating piece of software. Many viruses, however, are additionally configured to harm your computer by altering the way it works. Depending on the virus, these alterations may be as benign as displaying a message on a certain date, or as destructive as erasing your hard drive.

When an infected file is executed, or the computer is started from an infected disk, the virus itself is executed. Often, it lurks in memory, waiting to infect the next program that is run, or the next disk that is accessed. In addition, many viruses also perform a trigger event, such as displaying a message on a certain date, or deleting files after the infected program is run a certain number of times.

The majority of viruses are harmless, displaying messages or pictures, or doing nothing at all. Other viruses are annoying, slowing down system performance, or causing minor changes to the screen display of your computer. Some viruses, however, are truly menacing, causing system crashes, damaged files and lost data.

What are the different types of virus?

Boot sector viruses append themselves to floppy disks. If you leave an infected disk in your floppy drive when you turn your system on or reboot it, the virus copies itself onto the boot sector of your hard drive. You cannot get this virus from sharing files or by executing a program - only from an infected disk.

Program sector viruses fasten themselves to other programs. Most will piggyback on EXE or COM files, but they can infect any file that your computer runs when it launches a program.

Macro viruses affect the template used to create documents or spreadsheets, thereby infecting every document or spreadsheet opened with the program.

Email viruses can infect your computer before you even open an email. For example, a virus named 'Bubble Boy', which targets Outlook and Outlook Express, can be launched even if it only opens up in the preview window. Just highlighting the subject line in the preview window activates the code. It starts sending messages to everyone in your address book in an attempt to overload and crash the email server.

How to prevent my computer from becoming infected?

An ounce of prevention is worth a pound of cure!

Taking defensive action is the best solution to protect your computer from the many thousands of viruses that loom in cyberspace. The following steps may not completely protect you from viruses, but they can significantly reduce your chances of being harmed by them.

Install antivirus software. No antivirus software is capable of protecting you from all viruses, but they act as a resourceful companion by helping you to scan incoming files and shared floppy disks and will keep you abreast of the latest viruses.

Note: To be best protected, make sure that you update your antivirus software on a monthly basis.

Use diligence with all disks. Always scan disks from unknown sources with your antivirus software, especially disks that are shared by several people.

Download with care. Download all files from disks or shared files on a network into a special folder on your hard drive and scan them with your antivirus software.

Scan attachments before reading them. Some email programs will automatically open an attachment with the appropriate program. Disable this function so that you can scan attachments before they are opened.

Be wary of attachments in emails from friends that you were not expecting. Many viruses will email themselves to everyone on someone's address list, and include an innocuous sounding message like 'check this out' or 'let me know what you think of this'. If a friend sends you an email that has an attachment, and the message isn't personalized with your name and theirs, check with your friend to make sure that they were the one that actually sent you the message, rather than a virus on their computer that was masquerading as them.

WARNING! It is important to note that if you choose ASCII format to save your files, you will lose all of the formatting within the document. If formatting is important to you, stick to RTF.

Back it up! Back up everything in a safe place that is separate from your hard drive.

Do not use illegal or 'pirated' software on your machine. These software programs could be infected.

Use shareware with caution. Do not use shareware unless you are absolutely sure that the software is free of viruses.

What does Juno do to protect me from viruses?

Juno is serious about safeguarding you from harmful computer viruses. In order to provide the best possible online experience Juno automatically scans all messages sent by or intended for users for harmful viruses.

If a virus-infected email is addressed to a Juno member like yourself, our servers are setup to block the original message. Please note that if we block an affected email, you will not be notified.

What should I do if I received a virus-infected email?

Viruses are generally transmitted in the form of attachments. It does not spread unless you open the attachment.Your machine will not get infected if you merely saved the attachment.

To make sure an attachment you receive is virus free, always save it on your computer and scan it with your antivirus software. If it is infected, follow the removal instructions suggested by your antivirus software. Most antivirus software has the ability to detect and delete/clean the virus. However, it is very important to keep your antivirus software up-to-date so that it can detect all the latest viruses also.

For instructions on how to save an attachment in Email on the Web, click here.

If you would like to learn more about protecting your computer with antivirus software we recommend the AntiVirus software page.

How do I check a file attachment for viruses?

Instead of opening an attachment, save it on your computer and scan it with your antivirus software. A file containing a virus cannot do any damage until you open it, so saving the file is not dangerous in itself.

For instructions on how to save an attachment in Email on the Web, click here.

What should I do if my computer is infected?

If you believe your computer may have been infected with a virus, you should run a virus-scanning program and follow the advice of your antivirus software on how to remove the virus.

To learn more about protecting your computer with antivirus software, please visit the antivirus software page.